certs/Makefile

   1 #
   2 # Makefile for the linux kernel signature checking certificates.
   3 #
   4
   5 obj-$(CONFIG_SYSTEM_TRUSTED_KEYRING) += system_keyring.o system_certificates.o
   6
   7 ifeq ($(CONFIG_SYSTEM_TRUSTED_KEYRING),y)
   8
   9 $(eval $(call config_filename,SYSTEM_TRUSTED_KEYS))
  10
  11 # GCC doesn't include .incbin files in -MD generated dependencies (PR#66871)
  12 $(obj)/system_certificates.o: $(obj)/x509_certificate_list
  13
  14 # Cope with signing_key.x509 existing in $(srctree) not $(objtree)
  15 AFLAGS_system_certificates.o := -I$(srctree)
  16
  17 quiet_cmd_extract_certs  = EXTRACT_CERTS   $(patsubst "%",%,$(2))
  18       cmd_extract_certs  = scripts/extract-cert $(2) $@ || ( rm $@; exit 1)
  19
  20 targets += x509_certificate_list
  21 $(obj)/x509_certificate_list: scripts/extract-cert $(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(SYSTEM_TRUSTED_KEYS_FILENAME) FORCE
  22         $(call if_changed,extract_certs,$(SYSTEM_TRUSTED_KEYS_SRCPREFIX)$(CONFIG_SYSTEM_TRUSTED_KEYS))
  23 endif
  24
  25 clean-files := x509_certificate_list .x509.list
  26
  27 ifeq ($(CONFIG_MODULE_SIG),y)
  28 ###############################################################################
  29 #
  30 # If module signing is requested, say by allyesconfig, but a key has not been
  31 # supplied, then one will need to be generated to make sure the build does not
  32 # fail and that the kernel may be used afterwards.
  33 #
  34 ###############################################################################
  35 ifndef CONFIG_MODULE_SIG_HASH
  36 $(error Could not determine digest type to use from kernel config)
  37 endif
  38
  39 # We do it this way rather than having a boolean option for enabling an
  40 # external private key, because 'make randconfig' might enable such a
  41 # boolean option and we unfortunately can't make it depend on !RANDCONFIG.
  42 ifeq ($(CONFIG_MODULE_SIG_KEY),"certs/signing_key.pem")
  43 $(obj)/signing_key.pem: $(obj)/x509.genkey
  44         @echo "###"
  45         @echo "### Now generating an X.509 key pair to be used for signing modules."
  46         @echo "###"
  47         @echo "### If this takes a long time, you might wish to run rngd in the"
  48         @echo "### background to keep the supply of entropy topped up.  It"
  49         @echo "### needs to be run as root, and uses a hardware random"
  50         @echo "### number generator if one is available."
  51         @echo "###"
  52         openssl req -new -nodes -utf8 -$(CONFIG_MODULE_SIG_HASH) -days 36500 \
  53                 -batch -x509 -config $(obj)/x509.genkey \
  54                 -outform PEM -out $(obj)/signing_key.pem \
  55                 -keyout $(obj)/signing_key.pem 2>&1
  56         @echo "###"
  57         @echo "### Key pair generated."
  58         @echo "###"
  59
  60 $(obj)/x509.genkey:
  61         @echo Generating X.509 key generation config
  62         @echo  >$@ "[ req ]"
  63         @echo >>$@ "default_bits = 4096"
  64         @echo >>$@ "distinguished_name = req_distinguished_name"
  65         @echo >>$@ "prompt = no"
  66         @echo >>$@ "string_mask = utf8only"
  67         @echo >>$@ "x509_extensions = myexts"
  68         @echo >>$@
  69         @echo >>$@ "[ req_distinguished_name ]"
  70         @echo >>$@ "#O = Unspecified company"
  71         @echo >>$@ "CN = Build time autogenerated kernel key"
  72         @echo >>$@ "#emailAddress = unspecified.user@unspecified.company"
  73         @echo >>$@
  74         @echo >>$@ "[ myexts ]"
  75         @echo >>$@ "basicConstraints=critical,CA:FALSE"
  76         @echo >>$@ "keyUsage=digitalSignature"
  77         @echo >>$@ "subjectKeyIdentifier=hash"
  78         @echo >>$@ "authorityKeyIdentifier=keyid"
  79 endif
  80
  81 $(eval $(call config_filename,MODULE_SIG_KEY))
  82
  83 # If CONFIG_MODULE_SIG_KEY isn't a PKCS#11 URI, depend on it
  84 ifeq ($(patsubst pkcs11:%,%,$(firstword $(MODULE_SIG_KEY_FILENAME))),$(firstword $(MODULE_SIG_KEY_FILENAME)))
  85 X509_DEP := $(MODULE_SIG_KEY_SRCPREFIX)$(MODULE_SIG_KEY_FILENAME)
  86 endif
  87
  88 # GCC PR#66871 again.
  89 $(obj)/system_certificates.o: $(obj)/signing_key.x509
  90
  91 targets += signing_key.x509
  92 $(obj)/signing_key.x509: scripts/extract-cert $(X509_DEP) FORCE
  93         $(call if_changed,extract_certs,$(MODULE_SIG_KEY_SRCPREFIX)$(CONFIG_MODULE_SIG_KEY))
  94 endif